Peery r



(No Model.)

P. R. SKINNER. ELECTRICAL DENTAL PLUGGER.

AH DREW BGRAHAM. FHUTU-LITMD. WASHINGTON. D C.

NTTED STATES PATENT -EEicE.

PERRY R. SKIN NER, OF ONEONTA, NEV YORK, ASSIGNOR OF ONE-HALF TO ARTHUR S. BARNES, OF SAME PLACE.

ELECTRECAL DENTAL PLUGGER.

SPECIFICATION forming part of Letters atent No. 557,159, dated March 31, 1896.

Application filed May 6, 1895. Serial No. 548,223. (No model.)

To @ZZ whom t may concern:

Be it known that l, PERRY R. SKINNER, a citizen of the United States, residing at Oneonta, in the county of Otsego and State of New York, have invented a new and useful Improvement in Dental Pluggers, of which the following is a speciiication.

My invention relates particularly to that class of electrical apparatus known as elec- IO tric hammers or electric mallets, in which a reciprocating armature is employed to deliver blows upon a tool held against an obj ect.

In order to explain the principles of my invention I will describe an article embodying I 5 the same, and will then point out the novel features in the claims.

The article which I have selected for the purpose of illustration is a device combining an clectromagnet having an automatically 2O reciprocating` armature with a tool-holder provided at its lower end with a tool and dcsigned for use in the practice of dentistry.

Figure l is a front View of this device. Fig. 2 is a vertical crosssectional view of Fig. l

as cut by a plane passing through its axis and perpendicular to the plane of the paper, some of the parts not being in section. Fig. is a top view of the section .fr @c of Fig. 2.

Similar letters and numerals refer to corresponding parts throughout the several views.

The electromagnet consists of a coil of wire A, placed on a soft-iron core B, formed in the shape of a hollow cylinder having a flange l) on its lower end. A disk b similar to the 3 5 iiange b is fastened on its upper end and holds the coil in place. A cylindrical inclosin g case ll surrounds the coil and is suitably connected with the flange Into the lower end of the core B is screwed a hollow arm E, in which works a tool-holder in the form of a rod c, terminating at its lower end in a head O, in which any desired kind of tool, as c', may be held.

The rod c passes up through the hollow center of the core B and carries at its extreme upper 4 5 end a contact-point c2, preferably of platinum.

The armature D of the electromagnet extends over the top of the same and partly projects into the hollow center of the core B, and is supported and carried by a sleeve d, loosely surrounding the rod c above the hollow arm E and within the center of the core. This armature is normally held away from the pole of the magnet by means of a retracting-sprin g CZ, surrounding the sleeve d and interposed between the armature and the top of the hollow arm E. The armature is prevented from rising above the top of the rod c by means of a nut c3 on the latter, and is freed from jarring in its movements by a spring surrounding the nut c3 and held against the upper sur- 6o face of the armature.

At the point where the rod c enters the hollow arm E it carries a collar c, the lower edge of which by striking the shoulder e4 in the hollow arm limits the downward movement of the rod. This collar is provided with a feather c5, which works in a groove in the hollow arm and prevents the rod c from rotating about its axis, but leaves it free to reciprocate parallel to the same. Below the collar 7o c4 and surrounding the rod c is a loose sleeve c6, which is prevented from rising in the arm E by means of the shoulder e5. A helical spring c7, snrroundin g the rod an d interposed between the sleeve and the head O, forces the 7 5 rod downward. The shoulder e6 above the head O limits the upward movement of the rod. The space therefore through which it is free to reciprocate is equal to the distance, when the rod is in its lowest position, between 8o the shoulder e6 and the head O. The arm E is suitably insulated at c from the hand of the operator.

An arm 7L, overhanging the upper end of the rod c, is attached to the inclosing case H and suitably insulated therefrom and adjustable thereon, so as to be moved away from or toward the end of the rod. A spring h/ is carried by the overhanging arm h and is provided with a contact-plate h2, preferably of 9o platinum, placed directly above the platinum point c2, so that by forcing the rod c upward against the spring an electrical connection will be established.

The overhanging arm in the drawings is held in a strip h6 of suitable insulating material rendered adjustable on the inclosing ease ll by an adjusting-screw 715, working in a projection 71,4 on the case and bearing against the end of the insulating-strip- A set-screw Ico h? passing through the slot hs in the strip secures the same when adjusted.

The inclosing case H is preferably coilstructed of soft iron and is closely iitted around the iiange b, so as to form with the hollow core B a single magnet, of which the upper edge of the inclosing case constitutes one pole and the upper en d of the hollow core constitutes the opposite pole. It will thus be seen that both poles act directly upon the armature D.

The positive and negative wires Z and t, leading to a battery or other source of electrical supply, are properly insulated from each other and are connected to a universal joint '1n fn, carried by the inclosing case H and insulated therefrom by a strip h3 of any suitable insulator, electrical connections being made by the frictional contact of the bearings.

The special forni of universal joint shown in the drawings is obtained by means of four pivot-pins l., 2, 3, and 4, arranged diametrically opposite and so embedded in a mass 7a of insulating material as to be electrically connected in the pairs l 2 and 3 4, each pair, however, being insulated from the other. The pins l and 3 work in the bearings m and s, which form the terminations of the wiresZ and t, respectively, while the pins 2 and at work in the bearings n and r attached to the insulating-strip h3. ln order to obtain a better electrical connection than would be secured by the frictional contact between the pivot-pins and their respective bearings, pressure-pieces n and o" are shown attached to the bearings n and fr and pressing against the ends of their respective pivot-pins.

The wire Z is electrically connected with one end of the coil A through the bearings In and n of the universal joint mn and through the wire 0, and the other end of the coil is connected by the wire p with the overhanging arm h.

The frictional Contact between the rod c and the hollow arm E and the contact between the latter and the inclosing case electrically connects these parts, and by the short wire q attached to the inclosing case and the contact oi the bearings r and s of the universal joint they are connected with the Wire t.

The operation of the device is as follows: The tool c is pressed against an object, which forces the rod c with its contact point c2 against the contact-plate 71.2 and completes the circuit. rllhe armature is drawn toward the magnet and the sleeve CZ strikes the collar c4, delivering a blow to the tool-holder. By the movement thus imparted to the rod c relative to the magnet and its inclosing case the point c2 and the plate h2 separate and break the circuit, the armature returning to its upper position by the action of the spring d. As the tool is held pressed against the object, contact is immediately restored, and the operation is repeated, a succession of blows being imparted to the tool-holder.

Having now described a device embodying my invention, and without limiting myself to this particular construction, what I claim as new, and desire to secure by Letters Patent, is

l. The combination of an electromagnet, an armature, a tool-holder whose reciprocations are controlled by the movements of the armature, supply-wires leading to and from the electromagnet, and a device for maintaining the continuity of the electric circuit between the terminals ofthe supply-wires and the coil of the electromagnet comprising a swivel conneetion, substantially as speciiied.

2. The combination of an electromagnet, a vibratory armature, a tool-holder whose reciprocations are controlled by the vibration of the armature, means for making and breaking the circuit through the coil of the electromagnet, supply-wires leading to and from the electromagnet, and a device for maintaining the continuity of the electric circuit between the terminals of the supply-wires and the coil of the electromagnet comprising a swivel connection having two axes of motion at right angles to each other, substantially as speciiied.

The combination of an electromagnet having an interior bore or cavity,a tool-holder extending through said cavity and mounted to have a lengthwise movement therein, a sleeve encircling said tool-holder and movable independently of the latter, a stop against which said sleeve impinges to cause a movement of the tool-holder, an armature whose movements control the movements of the sleeve, and means for making and breaking the circuit through the coil of the electromagnet to cause the vibration of the armature substantially as specified.

4L. The combination of an electromagnet having an interior bore or cavity, atool-holder extending through said cavity and mounted to have a lengthwise movement therein, a sleeve encircling said tool-holder and movable independently of the latter, a stop against which said sleeve impinges to cause a movement of the tool-holder, an armature whose movements control the movements of the sleeve, and a make-and-break device interposed in the electric circuit through the coil of the electromagnet, comprising an arm supporting a contact-piece and a contact-piece moving simultaneously with the tool-holder, substantially as speciiied.

5. rlhe combination of an electromagnet comprising an inner and an outer cylindrical shell, a tool holder extending lengthwise through the bore of the inner shell and mounted to have a lengthwise movement therein, a piece comprising an armature movable toward and away from the electromagnet, a stop against which this piece impin ges to move the tool-holder, and means for causing the vibration of said piece to impart a reciprocating movement to the tool-holder, substantially as specified.

G. rlhe combination of an electromagnet, a tool-holder, a piece comprising an armature, movable independently of the tool-holder and IOO IIO

electric-al communication with said supplywires7 embedded in said insulating material and having ends projecting therefrom, and pieces in which said pivot-pins are j ournaled and through which the continuity of the eleotrie circuit is maintained, substantially as specified.

In testimony whereof I have signed my name to this specification in the presence of two subscribing` witnesses.

PERRY R. SKINNER. fitnessesz J. LEE FRIsBEE, ARTHUR S. BARNES. 

